Counterbalance means



Dec. 14, 1965 J. CHASTAIN 3,222,940

COUNTERBALANCE MEANS Filed Nov. 13, 1961 2 Sheets-Sheet I LOAD L851INVENTOR Joe Chustoin ATTORNEYS Dec. 14, 1965 J. CHASTAIN COUNTERBALANCEMEANS 2 Sheets-Sheet 2 Filed NOV. 13, 1961 Fig.6

INVENTOR Fig.9

Fig. 8 4 Joe Chostom Mi I BY W W ATTORNEYS United States Patent ()fiFice3,222,940 Patented Dec. 14, 1965 3,222,940 COUNTERBALANCE MEANS JoeChastain, PO. Box 4035, Midland, Tex. Filed Nov. 13, 1961, Ser. No.151,723 7 Claims. (CI. 74-41) This invention relates to counterbalancemeans for balancing unequal loads which are moved in alternatereciprocal movements and, more particularly, to counterbalance means forreducing the peak torques on the drive shaft of a power unit which isadapted to move the unequal reciprocating loads.

One object of this invention is to provide a new and improvedcounterbalance means for unequal reciprocating loads which are moved inreciprocation whereby the peaking of torque on the drive shaft of thepower unit moving such loads is reduced.

Another object of the invention is to provide a new and improvedcounterbalance means adapted for application to reciprocating movementpumps and to provide load equalizing means whereby the variations in theload on the motor driving the pump are minimized during each cycle ofoperation of the pump.

Still another object is to provide a new and improved pump, of thereciprocating movement type, having a counterbalance means whichautomatically varies in accordance with the reciprocating movement ofthe pull or lift rods of the pump to minimize the variations in the loadon the motor during each cycle of operation of the pump.

A further object is to provide a reciprocating movement type pumpincluding a pump jack and a mechanical linkage for translating therotary motion of a drive shaft to oscillating movement of the pump jacklever wherein the driving means directly connected to the pump jacklever for oscillating the same forms one side of a parallelogram linkagewhich maintains the angle between the driving means and pump jack leverat approximately ninety degrees and wherein the line of force applied toone end of the pump jack lever by said driving means is parallel to theline of force applied by the opposite end of said pump jack lever to thepull or lift rods of the pump throughout the upstroke and downstrokemovements of the pump jack lever, thereby effecting an efficienttransfer of energy between the drive shaft and pump lift rods.

A still further object is to provide a new and improved counterbalancemeans adapted for application to reciprocating movement pumps whereinthe effective force of a counterbalance mass or weight is varied duringeach cycle of operation of the pump to provide for a uniformdistribution of torque on the drive shaft of the motor driving the pump.

A still further object is to provide a new and improved counterbalancemeans adapted for application to reciprocating movement pumps whichvaries automatically in accordance with the reciprocating movement ofthe pull or lift rods of the pump to minimize variations in the load onthe motor driving the pump and to provide for a uniform distribution oftorque on the motor drive shaft during a cycle of operation of the pumpwithout any pronounced peaking.

Additional objects and advantages of the invention will be readilyapparent from the reading of the following description of a deviceconstructed in accordance with the invention, and reference to theaccompanying drawings thereof, wherein:

FIGURE 1 is a schematic fragmentary side view of a pump mechanismincluding a pump jack and counterbalance means therefor and showing theparts thereof in the positions they assume during the downstroke of thepump;

FIGURE 2 is a schematic fragmentary side view of the mechanism of FIGURE1 showing the parts thereof in the positions they assume during theupstroke of the pump;

FIGURE 3 is a fragmentary end view of the pump mechanism of FIGURE 1;

FIGURE 4 is a graphic comparison of the load capacitor with a constantinput torque of a unit with the counterbalance means of this inventionand a unit with a conventional counterbalance means;

FIGURE 5 is a schematic fragmentary side view of a pump mechanismincluding a pump jack and having a modified form of counterbalance meanstherefor and showing the parts thereof in the positions they assumeduring the downstroke of the pump;

FIGURE 6 is a schematic fragmentary side view of the mechanism of FIGURE5 showing the parts thereof in the positions they assume during theupstroke of the P p;

FIGURE 7 is a fragmentary end view of the pump mechanism of FIGURE 5;

FIGURE 8 is a graphic illustration of the torque imposed on the pumpmotor drive shaft by a conventional counterbalance means;

FIGURE 9 is a graphic illustration of the torque imposed on the pumpmotor drive shaft by the counterbalance means illustrated in FIGURES 5,6 and 7;

FIGURE 10 is a fragmentary side elevation of a modification of themechanism of FIGURE 1; and

FIGURE 11 is a fragmentry side elevation of a modified form of crank armand counterweight which may be used with either pump jack mechanism. 2

Referring now particularly to FIGURES l to 3 of the drawings, areciprocating movement pump jack mechanism 10 is shown mounted on a flatbase or support 11. The pump, itself, may be of a type suitable forpumping wells, such as oil wells, whereby a piston (not shown) may beattached in the usual manner to the pull or lift rods 13 of the pump andslidably mounted in a well flow conductor or casing which communicateswith a pool or reservoir of liquid to be pumped. The piston may beprovided with a conventional by-pass valve or gasket which will permitflow of liquid in the conductor past the piston during the downwardstroke of the lift rods and piston and which will prevent flow of liquidpast the piston during the upstroke of the lift rods and piston, therebycausing the liquid to be lifted out of the reservoir during theupstrokes of the lift rods and piston.

The lift rods are attached to an arcuate support or horsehead 14 at theend of the pump jack lever or walking beam 15 from which they aresuspended substantially vertically. A bracket. 17 attached to theunderside of the pump jack lever intermediate its ends is provided witha sleeve, saddle bearing or the like, for connection with a horizontallydisposed pivot bar or shaft 18 mounted in the upper ends of a supportframe 19. The support frame may include a substantially vertical Samsonpost 20 and an angular brace 20a. The pivot bar 18 thus provides afulcrum for the reciprocating oscillatory movements of the pump jacklever.

The end of the pump jack lever remote from the lift rods has a bracket21 attached to its underside providing a tail-bearing connection with ahorizontal pivot pin 21a which is connected at its ends to a pair ofpitman rods 22 by means of suitable bearing couplings 23. The pitmanrods extend downwardly parallel to each other and are pivotallyconnected at their lower ends to a drive crank or arms 24 by means ofpitman bearing couplings 25. Each of the couplings 25 receives ahorizontally disposed crank pin or pivot 27 carried by its associateddrive crank or arm at a point intermediate its ends. The drive cranksare mounted parallel to one another on opposite ends of a transmissiondriven shaft 28 of a speed reducer 29. The shaft 28 is driven by a driveshaft 30 of the speed reducer, being connected to the drive shaft by adrive chain 32, or other suitable means, such as a gear train, whichoperatively connects a driven sprocket 33 on the transmission drivenshaft with a drive sprocket 34 on the drive shaft. The drive shaft 30 isjournalled in a. pair of upright bearing supports 35 and 36 on the base11. The gears and chain of the speed reducer 29 are enclosed within ahousing or gear box case 37 having at its lower end a hollow bearingsleeve (not shown) which is journalled on the drive shaft 30 so that thespeed reducer housing may pivot about the drive shaft. The drive shaft30 has a pulley 39 rigidly secured thereon so that the drive shaft maybe rotated by a suitable belt (not shown) driven by a motor (not shown),in the usual manner.

A pair of auxiliary beams or levers 40 are each attached at one end to acoupling 40a rotatably disposed on the crank pins Or pivots 27. At itsother end each auxiliary beam is pivotally connected to the Samson post20 by a pivot pin 41 mounted in a bearing bracket 42 secured to theSamson post preferably substantially vertically below the pivot bar 18for the pump jack lever. As shown in FIGURES 1 and 2, the auxiliarybeams 44) are disposed parallel with the walking beam or pump jack lever15. The pitman rods 22, which are parallel to one another, are alsodisposed substantially parallel to the plane between the fulcrum pivot18 and the pivots 41 on the Samson post 20 and to. the pump lift rods13, thus describing a parallelogram linkage or framework wherein theauxiliary beams 40 constitute one side of the parallelogram and togetherwith the pump jack lever 15 comprise a first pair of opposite sides,while the pitman rods 22 which are connected to the pump jack andauxiliary beams also form one side of the linkage and are maintainedsubstantially parallel to the plane through the pivots 18 and 41 at theother side of the linkage. It will also particularly be seen that thepitman rods 22 are at all times maintained substantially parallel to thepump lift rods 13 by virtue of their connection with the pump jack lever15 and the auxiliary beams 40 of the parallelogram linkage which swingfrom the stationary support 19 to maintain the pitman rods in a verticalposition parallel to such lift rods during the swinging reciprocatingmovement of the pump jack lever. The lift rods 13 move in a verticalline because of their flexible connection with the horsehead 14. g

It will thus be apparent that the cranks 24, which are drivensimultaneously in a rotary movement about the transmission shaft 28 ofthe speed reducer, cause the pitman rods 22 and the end of the pump jacklever 15 which the pitman rods are secured to move downwardly relativeto the shaft 28 as the cranks are moved downwardly in acounter-clockwise direction as shown in FIGURE 2. Further, it will beseen that the pitman rods and the end of the pump jack lever to whichthey are secured move upwardly relative to the shaft 28 as the cranksmove upwardly in a counter-clockwise direction as shown in FIGURE 1.However, because of the provision of the auxiliary beams 40 which holdthe lower ends of the pitman rods, the gear box is forced to oscillatein a limited arc of pivotal movement about the shaft 30 as the cranksare rotated by the shaft 28. The speed reducer gear box is pivoted tothe right, as shown in FIGURE 2, when the cranks move downwardly; and tothe left, as shown in FIGURE 1, when the cranks move upwardly. Thear-cuate distance of pivotal movement of the speed reducer gear box ispreferably substantially equal to the vertical stroke of the pumpingunit lift rods.

Like the pump jack lever 15, the auxiliary beams 40 which hold the lowerends of the pitmans are also subjected to a limited pivotal movementabout their respective pivots 41 by the rotation of the cranks. Thus,the pitmans are moved laterally toward and away from the Samson posts 20during each cycle of rotation of the cranks, the amount of such lateralmovement being very small, since the arcs described by the pivoted endsof the pump jack lever and the auxiliary beams are small as compared tothe length of the lever arms forced thereby. Consequently, the pitmanrods 22 remain substantially vertical at all times and the force appliedthereto is substantially longitudinal thereof at all times, and isparallel to the force applied on the horsehead end of the crank jack bythe load acting on the pump lift rods.

It will be apparent that the torque on the drive shaft or power shaftcaused by the weight of the lift rods and piston, and the column offluid supported on the piston, will change during each cycle ofoperation of the pump. The peak torque load during the upstroke of therods will have a large positive value because of the weight of the liftrods and the fluid supported on the piston, whereas during thedownstroke the weight of the lift rods and such fluid as remains on thepiston will act to produce a negative torque on the shaft. Thus, it Wlllbe noted that the greater the weight of the column of fluid lifted, thegreater will be the peak torque on the driving shaft during thedownstroke and upstroke in each cycle of operation of the pump, and thegreater will be the loads imposed on the speed reducer and the motor.

To reduce these torque peaks, a counterbalance weight W is mounted oneach crank arm 24 at the end thereof which is remote from the drivenshaft 28 of the speed reducer, the mass of the weights and the distancesfrom the driven shaft 28 when the same are secured to the crank armsdetermining the effective force exerted by such weights. It will benoted that during the upstroke or lifting movement of the pump 10, asillustrated in FIGURE 2, the crank 24 and counterweights W apply orexert a downward force on the pitman rods and therefore on the end ofthe walking beam of the pump jack which is remote from the lift rods.Thus, during the upstroke movement of the lift rods, the counterweightsW assist the power shaft of the prime mover in lifting the lift rods 13and the column of fluid above the piston. During the downstroke movementof the elements, as illustrated in FIGURE 1, it will be noted that thecounterweights W exert their force in opposition to the swingingmovement of the crank arm and resist upward movement of the pitman rodsand the end of the pump jack remote from the lift rods. It will also benoted that when the counterbalance weights W are positioned as shown inFIGURE 2, during the upstroke of the pump jack, the counterweights actin conjunction with the force applied to the pitman rods by the crankarm and thus produce a larger downward force acting on the pitman rodsand on the pitman rod end of the pump jack lever to provide for theapplication of a greater lifting force to the lift rods 13. Thisarrangement therefore produces a greater effective downward forceapplied to the pitman end of the pump jack lever during the lifting orupstroke of the pump lift rods and a lesser or smaller effective forceon the pitman rod end of the pump lift rods, whereby the force appliedto the pitman rod end of the pump jack lever by the gear reducer, crankarms and counterweights varies in accordance with the load applied tothe horsehead end of the pump jack lever during the up and down strokesof the lift rods. It is believed obvious that the rotation of the crankarm may be in either direction, though it has been described ascounter-clockwise, and that rotation in either direction would producethe same effective force applied to the pitman rod end of the pump jacklever. The mass of the gear box always imposes a slight torque actingdownwardly on the pitman rods except when it is in vertical alignmentwith such rods.

It is also to be noted that the pitmans 22 remain or are held in aposition substantially parallel to the lift rods 13 throughout therotary movement of the cranks and the pivotal movements of the pump jacklever and the auxiliary beams. Thus, the angle between the pitmans andthe pump jack lever changes but slightly throughout the up and downstrokes of the pump, and never varies greatly from ninety degrees.Consequently the force exerted on the pump jack lever approaches theeificiency obtainable with an ideal infinite length pitman. Of course,the counterbalance weights do not impose any torque on the pitman rods22 when the crank arm 24 is in vertical alignment with the pitmans 22.

It will also be seen that the torque or force applied to or imposed onthe pivots 27 at the lower end of the pitman rods and the outer end ofthe auxiliary beams by the gear reducer and counterweights during eachcycle of operation of the pump will always be opposite to the torque onsuch pivots resulting from the weight of the lift rods and piston andthe column of fluid supported on the pump piston. The graphicillustration in FIGURE 4 provides a comparison of the loads which can belifted by a conventional pumping unit with the loads which can be liftedby a pumping unit having the parallelogram auxiliary beam constructionof this invention. In each case a constant torque is applied from thegear reducer 23 and a given counterbalance W is mounted on the crankarm. Curve A illustrates the maximum load capacity which can be liftedon the upstroke by the unit of this invention having the parallelogramauxiliary beam construction, and curve B illustrates the minimum loadcapacities which can be lifted on the downstroke of the same structure.The maximum load capacity which can be lifted by a conventional unit isillustrated in curve C showing the maximum load capacity for theupstroke of the unit. Curve D shows minimum load capacity for thedownstroke. If loads are greater on the upstroke or less on thedownstroke than the values indicated in the curves, then torque overload would result, with a torque applied to the gear reducer in excessof the capacity of the gear reducer. It will particularly be noted thatthe load capacity available applied during the major portion of themovement of the crank arm and of the pump jack unit of this invention issubstantially level and gives space for a rectangular substantiallyhorizontal dynamometer card without overloading the pumping unit for theparallelogram structure of this invention, as compared with thenecessarily angularly disposed dynamometer card required for thestandard counterbalance structure.

Referring now particularly to FIGURES 5 through 9 of the drawings, whichillustrate a preferred form of the pump jack mechanism, the pump jack110 comprises an upright support 111 which is mounted at one end of a.base 112. The support includes a pair of substantially A-shaped sideframes 111a and 11112. An elongate walking beam or pump jack lever 113is pivotally supported intermediate its ends on the top of the support111 by a saddle bearing connection or bracket 114 afiixed to the lowersurface of the pump jack lever which receives the horizontal pivot pin115 mounted on and extending between the side frames 111a and 11111. Oneend of the beam is provided with a horsehead 116 to which pump pull orlift rods 117 are attached and depend therefrom. The lift rods areadapted to be attached to a load (not shown) whereby the load may bemoved reciprocally upon oscillatory movement of the pump jack lever 113.For instance, a piston may be attached to the lift rods and moved withina well flow conductor or well casing for lifting fluid from anunderground reservoir. The piston may be provided with a valve ofconventional type which permits passage of fluid past the piston duringa downstroke thereof but prevents passage of fluid past the pistonduring the upstroke thereby thus causing the lifting or pumping of fluidfrom the reservoir upon oscillation of the pump jack lever 113.

The drive mechanism for oscillating the beam comprises a power or driveunit M, which may include a motor and a gear reducer or chain drive,supported at one end of the base 112 on a pedestal and is provided witha drive shaft 131. A crank arm 132 at one side of the power unit has oneend rigidly secured to one end of the drive shaft and a similar crankarm 133 at the other side of the power unit has one end rigidly securedto the other end of the drive shaft, the two arms being disposed inaligned parallel relationship to one another.

A pair of auxiliary beams 135 and 136 are pivotally connected at one endto the support 111 by suitable pins 137 and 138, respectively, andjournalled in axial alignment in the auxiliary beams. The auxiliarybeams 135 and 136 are connected to the crank arms 132 and 133, re-

spectively, by pins 140 and 141 rigidly secured to the v crank arms andextending laterally outwardly into elongate slots 142 of the auxiliarybeams. Roller sleeves 141a may be rotatably mounted on the pins andextend into the slots to reduce the friction between the pins and theparallel bearing surfaces 143 and 144 on opposite longitudinal sides ofthe slots, on which the roller sleeves ride.

It will be apparent that as the drive shaft of the motor rotates androtates the crank arms, the pins 140 and 141 will cause the auxiliarybeams 135 and 136 to oscillate about the auxiliary beam pivot pins 137and 138, respectively, due to their engagement with the bearing surfacesor shoulders defining the slots as the pins move longitudinally of theslots.

The auxiliary beams are also disposed parallel to the pump jack lever113 and connected thereto by a pair of pitman rods 146 and 147 and abracket bar 148. Oscillatory pivotal movement of the auxiliary beamscaused by the rotation of the crank arms also causes the oscillatingpivotal reciprocating movement of the pump jack lever 113.

The bracket bar 148 is secured to the underside of the pump jack lever113 at the end thereof which is remote from the horsehead, and isprovided at its ends with horizontally disposed pivot pins 150 and 151which are journalled in spaced pairs of lugs 152 and in the upper endsof the pitman rods 146 and 147, respectively. The pitman rods 146 and147 are connected at their lower ends to the auxiliary beams 135 and136, respectively, by pivot pins 153 which are journalled in the lowerends of the pitmans and the brackets 154 secured to the topsides of theauxiliary beams.

Weights 155 and 156 are secured to the ends of the crank arms 132 and133, respectively, remote from the drive shaft 131, while counterbalanceweights 158 and 159 are secured to the outer free ends of the auxiliarybeams 135 and 136, respectively.

It will thus be apparent that the auxiliary beams and the pitman rodscomprise a mechanical linkage which when activated by rotary movement ofthe crank arms 132 and 133 cause the oscillatory pivotal reciprocatingmovement of the pump jack lever 113.

As shown in FIGURES 5 and 6, the auxiliary beams are disposed parallelwith the pump jack lever or walking beam 113 and comprise therewith afirst pair of opposite sides of a parallelogram linkage, while thepitman rods form one side of the other pair of sides of theparallelogram, the plane through the pivot pins 115, 137 and 138 formingthe other side of such other pair of sides and being preferably disposedsubstantially parallel tothe pitman rods.

It will also be apparent that the torque on the drive shaft 131 of thegear reducer caused by the weight of the lift rods, the piston and thecolumn of fluid supported on the piston will change during each cycle ofthe pump. The peak torque load during the upstroke will have a largepositive value because of the weight of the lift rods and the fluidsupported on the piston, whereas during the downstroke the weight of thelift rods and such fluid as remains on the piston will act to produce anegative torque on the drive shaft. Thus, it will be noted that thegreater the weight of the lift rods and the column of fluid being liftedby or supported on the piston, the greater will be the peak torque onthe driving shaft during the upstroke and the downstroke in each cycleof operation of the pump, with the consequentially greater loads imposedon the gear reducer drive shaft 131.

To reduce these torque peaks, the counterbalance weights 158 and 159 aresecured to the outer free ends of the auxiliary beams, and the weights155 and 156 are mounted on each crank arm 132 and 133, respectively, at

the end thereof which is remote from the drive shaft 131 of the powerunit M, being disposed outwardly from the drive shaft beyond the rollers141a engaged in the slots 142 of the auxiliary beams. It will be notedthat during the upstroke or lifting movement of the pump 110, asillustrated in FIGURE 6, the crank arm weights 155 and 156 apply orexert a downward force on the auxiliary beams 135 and 136 complementingthe downward force exerted thereon by the counterbalance weights 158 and159 secured to the outer free ends of such auxiliary beams, and therebyexert a downward force on the pitman rods and on the end of the walkingbeam of the pumping jack to which the pitman rods are connected remotefrom the pump lift rod. Thus, during the upstroke movement of the liftrods, both the crank arm weights and the counterbalance weights assistthe power shaft or drive shaft of the motor in lifting the rods 117 anda column of fluid supported thereby above the piston. During thedownstroke movement of the elements, as illustrated in FIGURE 5, it willbe noted that the crank arm weights 155 and 156 are positioned betweenthe pitman rods 146 and 147 and the pivot 137 for the auxiliary beams,and that the effective lever arm of such weights is reduced in lengthand the force exerted by such Weights acts in opposition to the force ofthe drive shaft of the motor and exerts a restraining force on theupward movement of the auxiliary beams 135 and 136, whereby a lesserdownward force is applied through the auxiliary beams to the pitman rodsand to the end of the pump jack lever to which they are connected.

It will therefore be seen that the arrangement of the auxiliary beamparallelogram structure with the counterbalance Weights secured thereto,in combination with the crank arm weights carried by the crank arms,produces a greater effective downward force applied to the pitman rodend of the pump jack lever during the lifting or upstroke of the pumplift rods, and a lesser or smaller effective load on the pitman rod endof the pump jack lever during the return or downstroke of the pump liftrods. The effective load applied to the pitman rod end of the pump jacklever thus varies in accordance with the load applied to the horseheadend of the pump jack lever during the up and down strokes of the liftrods.

It is to be noted that the pitman rods 146 and 147 are held and remainin a substantially vertical position, or in a position substantiallyparallel to the pump lift rods 117, throughout the rotary movement ofthe cranks and the pivotal reciprocating movements of the pump jacklever and the auxiliary beams. The pitman rods are retained in suchposition by their connection with the auxiliary beams and the pump jacklever, since the pump jack lever and auxiliary beam are pivotallyconnected to the stationary upright support 111 and the auxiliary beamand pump jack lever move substantially parallel to each other throughouttheir arc of movement about their pivotal connections with the support.

It will be readily apparent that both the mass of the counterbalanceweights and the crank arm weights and the position of such weights onthe auxiliary beam and on the crank arms, respectively, may be varied asdesired to vary the effective force exerted on the pitman rods and thepump jack lever thereby.

For the purposes of comparison, a graphic illustration of the torqueimposed on the drive shaft by the load on the lift rods and the torqueimposed on the drive shaft by a conventional counterbalance means isshown in FIGURE 8 of the drawings, wherein it is noted that the netresultant torque shown in dotted lines becomes a negative torque duringa substantial portion of the pump cycle. In contrast to the conventionalstructure, a pump unit having a parallelogram counterbalance mechanismof this second form of the invention incorporated therein is illustratedgraphically in FIG- URE 9, and it is to be noted that the net resultingtorque imposed on the drive shaft by the lift rods and by thecounterbalance arrangement of the parallelogram linkage and weights onthe crank arm and auxiliary beam of this second form of the inventionproduces a positive torque at all times throughout the entire pumpcycle, and therefore produces a more satisfactory desirable resultWithout overloading of the equipment. Consequently, the parallelogramauxiliary counterbalance structure of this invention reducesfluctuations in the torque applied to the drive shaft, reduces themaximum torque applied thereto and permits less power to be applied tothe 'drive shaft for operation of the pump jack than is required forperforming the same amount of work with the conventional structure ofFIGURE 8.

It is readily apparent that, if desired, a counterbalance weight CW maybe applied to each of the auxiliary beams 40 of the form of theinvention first described and illustrated in FIGURES 1 and 2. Such amodified structure is shown in FIGURE 10, wherein the auxiliary beam 240is provided with an extension iarm 241 extending in longitudinalalignment therewith beyond the connecting bearing 240a by means of whichthe auxiliary beam is connected to the pivot 27 of the crank arm 24 ofthe unit first described. Obviously, the counterbalance CW in thismodification of the invention first described is supplemented by thecrank arm weight W in reducing the torque imposed on the transmissiondriven shaft 28 and the drive shaft 30 by the load exerted on .thehorsehead end of the pump jack lever during the upstroke of the pumplift rods, the crank arm weights and the counterbalance weights of thismodification coacting in a similar manner as the correspondingcounterbalance weights on the auxiliary beams and the crank arm weightson the crank arms of the second form of the invention.

It is further readily apparent that the crank arms 24 of the first formof the invention and the crank arms 132 of the second form of theinvention may be modified as shown in FIGURE 11 to position the crankarm weights W of the first form and and 156 of the second fornr withrespect to the crank arms to provide a lead or a lag in the effect ofthe force exerted by the weights through the crank arms on the auxiliarybeams of the respective parallelogram counterbalance linkages. In suchevent, the crank arm could be curved (not shown) or the crank arms maybe formed with a crank arm section 200 having openings 201 therein forreceiving the crank. pins .27 or140, as the case maybe, and a weightlever arm section 202 on which the crank arm weights 203 may be secured.As shown, the axis line through the crank arm openings 205 for receivingthe drive shaft and the openings 2M is disposed at arc angle to the axisline from the opening 205 through the center of mass of the weight 203.Thus, the center of mass of the weights would be moved either in advanceor behind the crank pins and the effect of the weights on the auxiliarybeams leads the crank pin or lag behind the crank pin as desired.

It will thus be seen that the counterbalance means of both forms of theinvention described herein provide for a more uniform distribution oftorque without producing the pronounced peaking present in conventionalunits. In addition, no negative torque is imposed on the drive shaft anda closer balance between maximum and minimum loads is effected.

It will further be seen that new and improved pump jack structures 'havebeen disclosed herein providing a parallelogram counterbalance meansminimizing variations in the load on the power unit or motor drive meansof the pump, reducing the torque peaks acting on the power unit andreducing the fluctuation of the torques acting on the unit.

The foregoing description of the invention is explanatory only, andchanges in the details of the construction illustrated may be made bythose skilled in the art, within the scope of the appended claims,without departing from the spirit of the invention.

What is claimed and desired to be secured by Letters Patent is:

1. A device of the type described including: a support means; anelongate walking beam pivotally mounted intermediate its ends at a fixedpoint on said support means for reciprocating oscillation about suchfixed point in a substantially vertical plane, one end of said walkingbeam being adapted to be connected to a reciprocably movable verticalload; an auxiliary beam member pivotally mounted at one end on saidsupport for swingable oscillation in a substantially vertical planeabout such pivotal connection with said support; a connecting linkmember pivotally connected at one end to the end of the walking beamopposite said reciprocably movable load and at its other end to saidauxiliary beam adjacent its outer swingable end, said link memberconnecting said elongate walking beam and said auxiliary beam parallelto each other, whereby said elongate walking beam is swingable about itspivotal mounting intermediate its ends by said auxiliary beam; a driveshaft carried by said support and rotatably mounted thereon; a crank armrigidly secured to said drive shaft and rotatable therewith; connectingmeans operatively interconnecting said crank arm and said auxiliarybeam, whereby said crank arm is connected with said elongate swingablewalking beam opposite the end of said walking beam to which said load isadapted to be connected for causing reciprocating oscillating movementof said walking beam upon rotary movement of said crank arm by saiddrive shaft; and a counterbalance weight means on said crank armoutwardly of said crank arm from said drive shaft beyond the connectionof said crank arm with said auxiliary beam for imposing a torque on saiddrive shaft; and second counterbalance weight means mounted on saidauxiliary beam at a point spaced outwardly from the pivotal connectionof said auxiliary beam on said support beyond the connection of saidauxiliary beam with the connecting link member, said secondcounterbalance weight means coacting with said first counterbalanceweight means on the crank arm for varying the load applied to saidwalking beam.

2. A device of the character set forth in claim 1 wherein the operativeconnection between the crank arm and the auxiliary beam comprises: aroller on said crank arm and an elongate longitudinally extending meanson said auxiliary beam engageable by said roller, whereby the rollerswings the auxiliary beam as the roller is moved by the crank arm, saidroller being movable on said auxiliary beam between an extreme outerposition outwardly of the auxiliary beam from the point of pivotalconnection of the auxiliary beam with the support beyond the point ofconnection of the connecting link member with said auxiliary beam and aninnermost position between said point of pivotal connection of saidauxiliary beam with said support and the point of connection of theconnecting link member with said auxiliary beam, whereby the effectivelength of the lever arm of the auxiliary beam varies with the positionof the roller in engagement with said elongate longitudinally extendingmeans on said auxiliary beam.

3. A pump jack mechanism including: a support, an elongate walking beammember pivotally mounted intermediate its ends at a fixed point on saidsupport for oscillating about such fixed point in substantially avertical plane, one end of said walking beam having means for connectingthe same to a reciprocably movable load; an auxiliary beam having oneend pivotally connected to said support and its other end free foroscillation in a substantially vertical plane; a connecting link memberpivotally connected at one end to the end of the walking beam oppositethe load connecting means, said connecting link member being pivotallyconnected at its other end to said auxiliary beam adjacent the free endthereof, the length of said connecting link member and said auxiliarybeam being such that the auxiliary beam is disposed parallel to saidwalking beam and said connecting link member is disposed substantiallyparallel to the plane of the pivots connecting the walking beam and theauxiliary beam to the support; first counterbalance weight means mountedon said auxiliary beam at a point spaced outwardly from the pivotalconnection thereof with the support beyond the connection of said linkmember with said auxiliary beam; a drive shaft; crank means connected tosaid drive shaft and rotatable about said drive shaft; means operativelyconnecting said crank means to said auxiliary beam adjacent theconnection of the connecting link member with said auxiliary beam,whereby rotation of said crank means by said drive shaft causes pivotalreciprocating movement of the auxiliary beam and the walking beamconnected therewith by said connecting link member; secondcounterbalance weight means on said crank means disposed outwardly ofsaid crank means from the drive shaft beyond the connection of the crankmeans with said auxiliary beam, said second counterbalance weight meansbeing moved through a path in which said second weight means is disposedat one extreme outwardly of said auxiliary beam beyond the point ofconnection of said connecting link member with said auxiliary beam andan inner extreme in which said second counterbalance weight means isdisposed inwardly of said point of connection of said connecting linkmember with said auxiliary beam toward the point of pivotal connectionof said auxiliary beam with said support for varying the torque forcesimposed on said auxiliary beam by said first counterbalance weight meansand said second counterbalance weight means as said crank means ismoved; and means for rotating said drive shaft to swing said crank meansand cause reciprocating movement of said auxiliary beam and the walkingbeam connected therewith.

4. A device of the character set forth in claim 3 wherein the operativeconnection between the crank means and the auxiliary beam comprises amovable connection shiftable longitudinally of said auxiliary beambetween an outer extreme outwardly of said auxiliary beam from thepivotal mounting of the beam on the support beyond the point ofconnection of the auxiliary beam with the connecting link member and aninner extreme inwardly of said auxiliary beam between the point ofconnection of the auxiliary beam with the connecting link member and thepivotal mounting of said auxiliary beam on the support whereby theeifective lever arm of the auxiliary beam is varied as said connectionbetween the crank arm and the auxiliary beam is moved longitudinally ofsaid auxiliary beam as the crank means is swung.

5. A device of the type described including: a support means; anelongate walking beam pivotally mounted intermediate its ends at a fixedpoint on said support means for reciprocating oscillation about suchfixed point in a substantially vertical plane; a reciprocably movablevertical load carried by one end of said elongate walking beam; anauxiliary beam pivotally mounted at one end to said support at a pointsubstantially vertically below said fixed point and extending parallelto said walking beam and swingable about said pivotal mounting on saidsupport in a substantially vertical plane parallel to said walking beam;a connecting link member pivotally connected at its opposite ends withsaid walking beam and with said auxiliary beam, one end of said linkmember being connected to the outer swingable end of the walking beamand the opposite end of said connecting link member being pivotallyconnected said auxiliary beam adjacent the outer end thereof oppositethe connection of said auxiliary beam with said support member, saidconnecting link member being disposed substantially parallel to the axisof movement of the reciprocably movable vertical load and providingmeans operatively connecting said walking beam and said auxiliary beamfor movement of said beams in parallel relationship as said beams areswung in a reciprocating oscillatory movement in said substantiallyvertical plane; a drive shaft carried by said support and rotatablymounted thereon; power means for rotating said drive shaft; a crank armrigidly secured to said drive shaft and rotatable therewith; connectingmeans operatively interconnecting the rotated end of said crank arm andsaid auxiliary beam adjacent the connection of said link member withsaid auxiliary beam, such operative connecting means providing aconnection between said crank arm and said walking beam at the end ofsaid walking beam opposite that to which said vertical load is connectedfor causing reciprocating oscillating movement of said beam upon rotarymovement of said crank arm by said drive shaft; first counterbalanceweight means mounted on the outer end of said auxiliary beam spacedlongitudinally outwardly beyond the connection of the link member withsaid auxiliary beam and beyond the connection of the crank arm with saidauxiliary beam; second counterbalance weight means; and means forconnecting said second counterbalance weight means with said drive shaftin an angularly offset relationship to the longitudinal axis of thecrank arm and outwardly from said drive shaft beyond the point ofconnection of said crank arm with said auxiliary beam for imposing atorque on said shaft and the crank arm driven thereby which varies inaccordance with the angular offset position of said secondcounterbalance weight means with respect to the axis of the crank arm,said second counterbalance weight means being movable through a path inwhich the mass of said second counterbalance weight means is disposedoutwardly of the auxiliary beam from the pivotal mounting of saidauxiliary beam on said support beyond the point of connection of saidconnecting link member with said auxiliary beam and beyond theconnection of the crank arm with said auxiliary beam and an innerposition with respect to said auxiliary beam in which said mass of saidsecond counterbalance weight member is disposed inwardly of the point ofconnection of said connecting link member with said auxiliary beam andbetween the connection of the crank arm with said auxiliary beam and thepivotal mounting of said auxiliary beam on said support whereby saidfirst and second counterbalance weights coact for varying the forceapplied to the walking beam and for limiting the net torque imposedthrough the crank arm and drive shaft on the power means as the walkingbeam is oscillated in moving the vertical load.

6. A device of the character set forth in claim 5 wherein the operativeconnection between the crank arm and the auxiliary beam comprises: aroller on said crank arm and an elongate longitudinally extending meanson said auxiliary beam engageable by said roller, whereby the rollerswings the auxiliary beam as the roller is moved by the crank arm, saidroller being movable on said auxiliary beam between an extreme outerposition outwardly of the auxiliary beam from the point of pivotalconnection of the auxiliary beam with the support beyond the point ofconnection of the connecting link member with said auxiliary beam and aninnermost position between said point of pivotal connection of saidauxiliary beam with said support and the point of connection of theconnecting link member with said auxiliary beam, whereby the effectivelength of the lever arm of the auxiliary beam varies with the positionof the roller in engagement with said elongate longitudinally extendingmeans on said auxiliary beam.

7. A device of the type described including: a support means; anelongate walking beam pivotally mounted intermediate its ends at a fixedpoint on said support means for reciprocating oscillation about suchfixed point in a substantially vertical plane; a reciprocably movablevertical load carried by one end of said elongate walking beam; anauxiliary beam pivotally mounted at one end to said support andextending parallel to said walking beam and swingable about said pivotalmounting on said support in a substantially vertical plane with saidwalking beam; a connecting link member pivotally connected at itsopposite ends with said walking beam and with said auxiliary beam, oneend of said link member being pivotally connected to said auxiliary beamadjacent the swingable end thereof opposite the connection of saidauxiliary beam with said support member, said connecting link memberproviding means operatively connecting said walking beam and saidauxiliary beam for movement of said beams in parallel relationship assaid beams are swung in a reciprocating oscillatory movement in asubstantially vertical plane, said connecting link member being movablein a vertical plane and parallel to the vertical load at said one end ofsaid walking beam; a drive shaft carried by said support and rotatablymounted thereon; a crank arm rigidly secured to said drive shaft androtatable therewith; connecting means operatively interconnecting theswingable crank arm and said auxiliary beam adjacent the connection ofsaid link member with said auxiliary beam, such connecting meansproviding a connection between said crank arm and said walking beam atthe end of said walking beam opposite that to which said load isconnected for causing reciprocating oscillating movement of said beamupon rotary movement of said crank arm by said drive shaft; and acounterbalance means connected with said crank arm and disposedoutwardly of said crank arm from the drive shaft beyond the point ofconnection of said crank arm with said auxiliary beam, whereby saidcounterbalance means imposes a weight load on said crank arm which ismovable between a point outwardly of said auxiliary beam beyond thepoint of connection of said connecting link member with said auxiliarybeam and a point in which said weight load is disposed inwardly of saidauxiliary beam between the point of connection of said connecting linkmember with said auxiliary beam and the pivotal mounting of saidauxiliary beam on said support for imposing a torque on said drive shaftwhich varies with the torque imposed on said drive shaft by saidreciprocably movable load; second counterbalance weight means mounted onsaid auxiliary beam at a point spaced outwardly from the pivotalmounting of said auxiliary beam on said support beyond the connection 13of said beam with the connecting link member, said second counterbalanceweight means coacting with said first counterbalance means of said crankarm for varying the load applied to said walking beam.

References Cited by the Examiner UNITED STATES PATENTS 735,518 8/1903Hussey 7441 1,495,218 5/1924 Allen 74--41 1,564,320 12/1925 Callahan7441 1,592,391 7/ 1926 Stevenson 7441 Reschke 7441 Crites et a1 74603Jackson 7441 Fuller 7448 Holzer 7441 Holzer 74103 Hartgerin g et a1.7441 Wineman 7441 Chasteun 7441 Egan et al. 74589 BROUGHTON G. DURHAM,Primary Examiner.

1. A DEVICE OF THE TYPE DESCRIBED INCLUDING: A SUPPORT MEANS; AN ELONGATE WALKING BEAM PIVOTALLY MOUNTED INTERMEDIATE ITS ENDS AT A FIXED POINT ON SAID SUPPORT MEANS FOR RECIPROCATING OSCILLATION ABOUT SUCH FIXED POINT IN A SUBSTANTIALLY VERTICAL PLANE, ONE END OF SAID WALKING BEAM BEING ADAPTED TO BE CONNECTED TO A RECIPROCABLY MOVABLE VERTICAL LOAD; AN AUXILARY BEAM MEMBER PIVOTALLY MOUNTED AT ONE END ON SAID SUPPORT FOR SWINGABLE OSCILLATION IN A SUBSTANTIALLY VERTICAL PLANE ABOUT SUCH PIVOTAL CONNECTION WITH SAID SUPPORT; A CONNECTING LINK MEMBER PIVOTALLY CONNECTED AT ONE END TO THE END OF THE WALKING BEAM OPPOSITE SAID RECIPROCABLY MOVABLE LOAD AND AT ITS OTHER END TO SAID AUXILIARY BEAM ADJACENT ITS OUTER SWINGABLE END, SAID LINK MEMBER CONNECTING SAID ELONGATE WALKING BEAM AND SAID AUXILIARY BEAM PARALLEL TO EACH OTHER, WHEREBY SAID ELONGATE WALKING BEAM IS SWINGABLE ABOUT ITS PIVOTAL MOUNTING INTERMEDIATE ITS ENDS BY SAID AUXILIARY BEAM; A DRIVE SHAFT CARRIED BY SAID SUPPORT AND ROTATABLY MOUNTED THEREON; A CRANK ARM RIGIDLY SECURED TO SAID DRIVE SHAFT AND ROTATABLE THEREWITH; CONNECTING MEANS OPERATIVELY INTERCONNECTING SAID CRANK ARM AND SAID AUXILIARY BEAM, WHEREBYS AID CRANK ARM IS CONNECTED WITH SAID ELONGATE SWINGABLE WALKING BEAM OPPOSITE THE END OF SAID WALKING BEAM TO WHICH SAID LOAD IS ADAPTED TO BE CONNECTED FOR CAUSING RECIPROCATING OSCILLATING MOVEMET OF SAID WALKING BEAM UPON ROTARY MOVEMENT OF SAID CRANK ARM BY SAID DRIVE SHAFT; AND A COUNTERBALANCE WEIGHT MEANS ON SAID CRANK ARM OUTWARDLY OF SAID CRANK ARM FROM SAID DRIVE SHAFT BEYOND THE CONNECTION OF SAID CRANK ARM WITH SAID AXUILIARY BEAM FOR IMPOSING A TORQUE ON SAID DRIVE SHAFT; AND SECOND COUNTERBALANCE WEIGHT MEANS MOUNTED ON SAID AUXILIARY BEAM AT A POINT SPACED OUTWARDLY FROM THE PIVOTAL CONNECTION OF SAID AUXILIARY BEAM ON SAID SUPPORT BEYOND THE CONNECTION OF SAID AUXILIARY BEAM WITH THE CONNECTING LINK MEMBER, SAID SECOND CONTERBALANCE WEIGHT MEANS COACTING WITH SAID FIRST COUNTERBALANCE WEIGHT MEANS ON THE CRANK ARM FOR VARYING THE LOAD APPLIED TO SAID WALKING BEAM. 